The Experts below are selected from a list of 150063 Experts worldwide ranked by ideXlab platform
Greg Leslie - One of the best experts on this subject based on the ideXlab platform.
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a numerical approach to Module Design for crossflow vacuum membrane distillation systems
Journal of Membrane Science, 2016Co-Authors: Oyue Lia, Yua Wang, Pierre Leclech, Vicki Che, Greg LeslieAbstract:A numerical model for heat and mass transfer in vacuum membrane distillation (VMD) under laminar flow was developed using Computational Fluid Dynamics (CFD). Three-dimensional (3D) simulations of temperature and concentration polarization in single and multiple fibre VMD Modules were used to estimate permeate flux (kg m(-2) h(-1)) over a range of temperatures (30-70 degrees C), vacuum pressures (10-100 mmHg), crossflow velocities (0.0072-0.72 m/s), and feed concentrations (0-0.4 kg/L NaCl). Simulated flux differed by less than 7% from experimental data for a Module with comparable dimensions. Simulations indicate that a 56% increase in fibre packing density resulted in a 24% flux decline at high operating temperature (70 degrees C), and more than 50% flux decline at low crossflow velocity (0.0072 m/s). The effect of vacuum pressure on flux was found to be independent to the Module packing density, while the effect of salt concentration was found to be 28% lower than estimates based on Raoult's law, due to lower spatial variations in membrane surface temperatures at higher salt concentrations. The approach developed in this paper may be used to evaluate performance of alternative configurations for VMD models to aid Module Design, scale-up and process optimization.
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a numerical approach to Module Design for crossflow vacuum membrane distillation systems
Journal of Membrane Science, 2016Co-Authors: Boyue Lian, Pierre Leclech, Vicki Chen, Yuan Wang, Greg LeslieAbstract:Abstract A numerical model for heat and mass transfer in vacuum membrane distillation (VMD) under laminar flow was developed using Computational Fluid Dynamics (CFD). Three-dimensional (3D) simulations of temperature and concentration polarization in single and multiple fibre VMD Modules were used to estimate permeate flux (kg m−2 h−1) over a range of temperatures (30–70 °C), vacuum pressures (10–100 mmHg), crossflow velocities (0.0072–0.72 m/s), and feed concentrations (0–0.4 kg/L NaCl). Simulated flux differed by less than 7% from experimental data for a Module with comparable dimensions. Simulations indicate that a 56% increase in fibre packing density resulted in a 24% flux decline at high operating temperature (70 °C), and more than 50% flux decline at low crossflow velocity (0.0072 m/s). The effect of vacuum pressure on flux was found to be independent to the Module packing density, while the effect of salt concentration was found to be 28% lower than estimates based on Raoult's law, due to lower spatial variations in membrane surface temperatures at higher salt concentrations. The approach developed in this paper may be used to evaluate performance of alternative configurations for VMD models to aid Module Design, scale-up and process optimization.
Douglas R Lloyd - One of the best experts on this subject based on the ideXlab platform.
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membrane distillation i Module Design and performance evaluation using vacuum membrane distillation
Journal of Membrane Science, 1996Co-Authors: Kevi W Lawso, Douglas R LloydAbstract:Pure water vacuum membrane distillation (VMD) experiments were performed to evaluate the heat and mass transfer boundary layer resistances in a new laboratory-scale membrane Module. The membrane Module Designed for this work is unique in that it can use flat-sheet membranes without a support. Additionally, the membrane Module and associated apparatus were Designed to achieve relatively high feed and permeate Reynolds numbers within the Module. These two factors led to a dramatic reduction in boundary layer resistances, which resulted in improved VMD fluxes. This paper also examines a new complete VMD model based on the dusty-gas model, which accounts for both Knudsen and viscous mass transport across the membrane. The new model was used to predict the performance of VMD with pure water and ethanol-water solutions.
E Chardon - One of the best experts on this subject based on the ideXlab platform.
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submerged hollow fibre membrane Module Design options and operational considerations
Desalination, 2002Co-Authors: Anthony G. Fane, Sheng Chang, E ChardonAbstract:A new membrane Module concept, the submerged hollow fibre membrane, has been widely accepted for the wastewater membrane bioreactor. This paper focuses on operational considerations and Design aspect of the submerged hollow fibre membrane Module. Experiments with both crossflow and ‘dead-end’ submerged systems have demonstrated that bubbling is effective in enhancing filtration performance, but the effect of gas flow rate is constrained because of the limited effect of bubbling on turbulence in two-phase flow. The experimental results also indicated that Module configuration exerts crucial effects on the performance of the system. A better filtration performance can be obtained with vertical axial fibre orientation, small fibre diameters, and a loose fibre bundle. A model describing the filtration behavior of the submerged hollow fibre at steady state shows that when the maximum initial flux is lower than the critical flux, the flux distribution along the fibre can be estimated according to a dimensionless parameter x = 4LRi−32Rm−12 which includes fibre length and radius and hydraulic resistance. When the average imposed flux is lower than the critical flux but the maximum local initial flux is higher than the critical flux, a steady state can be achieved after an initial deposition over some of the fibre length. The filtration resistance caused by the initial deposition becomes significant when the fibre radius is smaller than 0.2 mm, particularly with long fibre lengths and high ratios of average imposed flux to critical flux. The simulation also suggested that the optimal combination of fibre radius and length goes to small radius and short length.
Raja Ghosh - One of the best experts on this subject based on the ideXlab platform.
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effect of Module Design on the efficiency of membrane chromatographic separation processes
Journal of Membrane Science, 2006Co-Authors: Raja Ghosh, Tiffany WongAbstract:Abstract The efficiency of membrane chromatography is critically dependent on membrane Module Design. This paper discusses the vital role of fluid flow distribution and collection within a membrane Module in membrane chromatographic processes. The performances of membrane Modules of three different diameters based on a new Design which enhanced both feed flow distribution and effluent collection were compared with corresponding conventional Modules. Protein bioseparation being one of the major applications of membrane chromatography, these studies were carried out using lysozyme as test solute. The lysozyme binding capacities of cation-exchange membranes housed in the different Modules were measured both in the breakthrough mode and in the pulse chromatographic mode. The membrane Modules based on the new Design showed significantly higher lysozyme binding capacities than the corresponding conventional Modules. The binding capacity enhancement due to Module Design increased with increase in membrane diameter. With the largest diameter membrane Module, the breakthrough binding capacity enhancements with the new Design were in the range of 110–112%. With the same diameter membrane Module the maximum binding capacity enhancements in the pulse chromatographic mode was found to be around 135%. The reasons for the increase in binding efficiency are explained.
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enhancement of membrane permeability by gas sparging in submerged hollow fibre ultrafiltration of macromolecular solutions role of Module Design
Journal of Membrane Science, 2006Co-Authors: Raja GhoshAbstract:Permeability in membrane filtration processes suffers from two major limiting factors: concentration polarization and membrane fouling. Gas-sparging, which involves bubbling of a gas in close proximity of a membrane, is known to minimise both of these. Gas-sparged membrane filtration is carried out either by pressurising a gas-sparged feed side or by using suction to draw the permeate through a membrane from the un-pressurised, gas-sparged feed side. The first approach is mainly used in ultrafiltration processes. The second approach which is easier to implement and is widely used in microfiltration processes. This paper discusses the enhancement of permeability by gas-sparging in suction-driven, submerged hollow fibre ultrafiltration using two different membrane Module types. These Modules were prepared using hollow fibre membranes having nominal MWCO of 150 kDa and were used to ultrafilter polysaccharide solutions. Depending on the operating conditions and on the Module Design, gas-sparging enhanced effective hydraulic permeability by as much as 115%. The extent of membrane fouling was also significantly lower in the gas-sparged mode. The effectiveness of gas-sparging was found to be greater with one membrane Module type, clearly highlighting the effect of Module Design on process efficiency.
Pierre Leclech - One of the best experts on this subject based on the ideXlab platform.
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a numerical approach to Module Design for crossflow vacuum membrane distillation systems
Journal of Membrane Science, 2016Co-Authors: Oyue Lia, Yua Wang, Pierre Leclech, Vicki Che, Greg LeslieAbstract:A numerical model for heat and mass transfer in vacuum membrane distillation (VMD) under laminar flow was developed using Computational Fluid Dynamics (CFD). Three-dimensional (3D) simulations of temperature and concentration polarization in single and multiple fibre VMD Modules were used to estimate permeate flux (kg m(-2) h(-1)) over a range of temperatures (30-70 degrees C), vacuum pressures (10-100 mmHg), crossflow velocities (0.0072-0.72 m/s), and feed concentrations (0-0.4 kg/L NaCl). Simulated flux differed by less than 7% from experimental data for a Module with comparable dimensions. Simulations indicate that a 56% increase in fibre packing density resulted in a 24% flux decline at high operating temperature (70 degrees C), and more than 50% flux decline at low crossflow velocity (0.0072 m/s). The effect of vacuum pressure on flux was found to be independent to the Module packing density, while the effect of salt concentration was found to be 28% lower than estimates based on Raoult's law, due to lower spatial variations in membrane surface temperatures at higher salt concentrations. The approach developed in this paper may be used to evaluate performance of alternative configurations for VMD models to aid Module Design, scale-up and process optimization.
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a numerical approach to Module Design for crossflow vacuum membrane distillation systems
Journal of Membrane Science, 2016Co-Authors: Boyue Lian, Pierre Leclech, Vicki Chen, Yuan Wang, Greg LeslieAbstract:Abstract A numerical model for heat and mass transfer in vacuum membrane distillation (VMD) under laminar flow was developed using Computational Fluid Dynamics (CFD). Three-dimensional (3D) simulations of temperature and concentration polarization in single and multiple fibre VMD Modules were used to estimate permeate flux (kg m−2 h−1) over a range of temperatures (30–70 °C), vacuum pressures (10–100 mmHg), crossflow velocities (0.0072–0.72 m/s), and feed concentrations (0–0.4 kg/L NaCl). Simulated flux differed by less than 7% from experimental data for a Module with comparable dimensions. Simulations indicate that a 56% increase in fibre packing density resulted in a 24% flux decline at high operating temperature (70 °C), and more than 50% flux decline at low crossflow velocity (0.0072 m/s). The effect of vacuum pressure on flux was found to be independent to the Module packing density, while the effect of salt concentration was found to be 28% lower than estimates based on Raoult's law, due to lower spatial variations in membrane surface temperatures at higher salt concentrations. The approach developed in this paper may be used to evaluate performance of alternative configurations for VMD models to aid Module Design, scale-up and process optimization.
